Kinetics and nucleation dynamics in ion-seeded atomic clusters

The time-dependent kinetics of formation and evolution of nanosize atomic clusters is investigated and illustrated with the nucleation dynamics of ion-seed ArnH+ particles. The rates of growth and degradation of Ar-atomic shells around the seed ion are inferred from molecular dynamics (MD) simulations. Simulations of cluster formation have been performed with accurate quantum-mechanical binary interaction potentials. Both the nonequilibrium and equilibrium growth of ArnH+ are investigated at different temperature and densities of the atomic gas and seed ions. Formation of Arn,40 shells is the main mechanism which regulates the kinetics of nanocluster growth and the diffusive fluctuations of the cluster size distribution. The time evolution of the cluster intrinsic energy and cluster size distributions are analyzed at the nonthermal, quasiequilibrium, and thermal equilibrium stages of ArnH+ formation. We have determined the self-consistent model parameters for the temporal fluctuations of the cluster size and found coefficients of the diffusive growth mechanism describing the equilibrium distribution of nanoclusters. Nucleation of haze and nanodust particles in astrophysical and atmospheric ionized gases is discussed.